[immortl]

Just posting a followup in case anyone else with a similar question comes across this in the future.

I went through and removed about 12-15 bio balls at a time. I let about 7-10 days pass between each removal (coincided with several periods of out of town travel for work, if I had been home, I probably would have done it with slightly shorter intervals). For the last removal, I was down to the point where the remaining bio balls would have been constantly under water so I figured it was no longer a wet/dry system and I pulled all of the remaining bio balls (about 20) out. Overall I removed the bio balls in about 5 steps over the course of 5 weeks.

I did a 50% water change and vacuumed out all of the rear chambers thoroughly. I then installed the media rack with poly filter / purigen / chemipure elite and put in the refugium rack as well. I scraped the paint off the back of the tank, attached the JBJ nano glo refugium lights, moved the macro algae I had in the DT to the refugium and called it good.

Prior to the cut over my nitrate levels were elevated between 20-40ppm. Since the cutover and thorough cleaning, they have been back down to 0. Woohoo! I understand the bio balls did not directly cause elevated nitrate levels and have surmised that the thorough cleaning of the rear chambers (lots of detritus under the false floors of both chambers 1 and 2) probably had more impact on lowering the nitrate levels than removing the bio balls.

I am very pleased with the filtration setup now, having an area for macro algae and being able to reduce the amount of it in the DT (although I do still like some green in there) is nice. The 'polish' on the water from the purigen/chemipure elite is nice too, as is the cheaper floss that I can now change more frequently. I am quite happy with the results and glad that I did this.